The arrival of the Silver Ranger in episode 25. Gargotron had the GPX and Flash Rangers down for the count when someone in a trenchcoat shows up, morphs, and beats Gargotron! Okay, so maybe Gargotron didn't have the guy's fight data, but it was still impressive.
Marty in SIU, showing worthy of being a Ranger by punching the local Dark Mistress. In the face!
Sean, Maria and Aaron (Mandla) get credit for fighting an Ouroboros Society monster while hungover!